During startup a Caché/Ensemble/HealthShare instance must consult a parameter file to get some information it needs at the early stages of startup. By default it uses the file called cache.cpf, but by adding an extra argument to the ccontrol start command you can make it use an alternative file.
One scenario where this might be useful is if you need to start an ECP data server in a mode that prevents application servers from connecting to it. Copy your cache.cpf file into one called, say, noecp.cpf and edit that file with any text editor, changing the MaxServerConn value in the
[config] section to 0. Then stop your Cache instance (named CACHE in this example) and restart it so it uses the alternative CPF file: ccontrol start CACHE /full/path/to/noecp.cpf
More documentation about CPFs is available here.
If you make use of alternative CPFs please add a comment below to describe your use-case.